People who get less than six hours of sleep per night have an increased of dying early．
A. custom
B. practice
C. disadvantage
D. risk
网友回答
A. custom
B. practice
C. disadvantage
(答案→)D. risk
解析：词义辨析。 A．习惯；风俗 B．实践；练习 C．缺点 D．风险；冒险。句意：每晚睡觉少于六小时睡眠的人有一个正在增加的早逝的风险。故选D。